If triangle RST is an acute triangle, then m∠S must be

a. less than 90°.

b. equal to 90°.

c. equal to 100°.

d. greater than 90° and less than 180°.

If triangle RST is an acute triangle, then m∠S must be

a. less than 90°.

b. equal to 90°.

c. equal to 100°.

d. greater than 90° and less than 180°.