The description which correctly explains the deaths of Cassius and Brutus is: Cassius asks Pindarus to kill him with his own sword; Brutus runs onto his own sword, which is held by Strato.
Cassius now instructs Pindarus to kill him (See Lines 36-46) which he does, while Cassius exclaims "Caesar, thou art reveng'd, / Even with the sword that kill'd thee " before dying (see Line 45).