The correct option is D Riya was very sad
An idiomatic expression is a type of informal English where the meaning
of the expression is different than the literal meaning of the
expression.
The underlined words "Riya was heartbroken" form an idiomatic expression. Her heart did not literally break, but 'heartbroken' means 'to suffer from emotional grief'.
Option B: This option gives the correct meaning of the idiomatic expression (grief means sadness), hence B is correct.
Option A: This meaning is different from the meaning of the idiom (she was affected emotionally, her heart did not suffer from an attack). Hence A is incorrect.
Similarly, the words 'heartache' and 'broke away' do not refer to the emotional pain that Riya had gone through ('heartache' is used in romantic relationships and 'broke away' is an idiom itself that refers to 'escaping from physical restraint). Hence options C and D are incorrect.