hide/show subgrid that contains another entity, based on a value?

Hi,

So here's the situation:

Account entity has an option set (ex. Optionset) with a 3 different values.

The Account form has a related entity, History, in a subgrid (ex. subgrid_history).

I want to keep the subgrid hidden by default and show only when Optionset equals to value "Customer".

Q1: How can this be achieved?

Q2: Can this be achieved using a workflow too?

Thanks!

SB