Which of the following cases upheld the requirement that plaintiffs demonstrate scienter when bringing action under the

Question:

Which of the following cases upheld the requirement that plaintiffs demonstrate scienter when bringing action under the Securities Exchange Act of 1934?
a. Ernst & Ernst v. Hochfelder.
b. Escott v. BarChris Construction Corp.
c. Smith v. London Assurance Corp.
d. Ultramares.