That is not possible with single-select fields, but you could do that by changing both of your fields into linked record fields, and then you could use Airtable’s dynamic filtering feature.

However, Airtable has made this somewhat complicated to setup, and it has to be setup for your ENTIRE BASE — not just the form itself. So anywhere you see those fields in Airtable, they will have the dynamic behavior attached to it.

A possibly easier option for doing this is to use Fillout’s advanced forms for Airtable.

You would only need to turn your second field into a linked record field (instead of both fields), and Fillout makes the setup process much easier. (Also, your linked record field can work differently on your Fillout form than how it works in your base.)

You can read more about this feature here: How to select and filter Airtable linked records in a dropdown

Fillout is 100% free, and it offers hundreds of features that Airtable’s native forms don’t offer, including the ability to update Airtable records using a form, create PDF files from form submissions, display Airtable lookup fields on forms, create new linked records on a form, control access to a form via SSO or email domains, perform math or other live calculations on your forms, accept payments on forms, collect signatures on a form, create multi-page forms with conditional paths, connect a single form to dozens of external apps simultaneously, add CAPTCHAs to your form, and much more.

I show how to use a few of the advanced features of Fillout on these 2 Airtable podcast episodes:

• Using Fillout to create an eSignature approval process with PDF file creation.
• Using Fillout to create an order entry form with line items.

Hope this helps! If you’d like to hire the best Airtable consultant to help you with anything Airtable-related, please feel free to contact me through my website: Airtable consultant — ScottWorld

To add on to Scott’s suggestions, I’ll just say that Airtable doesn’t support filtering options dependent on the same field (which it seems like what you want, just one Task field). 

I could think of some ways to approach this using additional fields, conditional views, and automation but it’d be quite a lot (something like other single select fields that only appear on condition of Task, and when modified automatically update the Task field).