When There Is a Single Instrument and Single Regressor, the TSLS

Multiple Choice

When there is a single instrument and single regressor, the TSLS estimator for the slope can be calculated as follows:

A) $\hat { \beta } _ { 1 } ^ { \text {TSLS } } = \frac { S _ { Z Y } } { S _ { Z x } }$
B) $\hat { \beta } _ { 1 } ^ { \text {TSLS } } = \frac { S _ { X Y } } { S _ { X } ^ { 2 } }$
C) $\hat { \beta } _ { 1 } ^ { \text {TSLS } } = \frac { S _ { Z X } } { S _ { Z Y } }$
D) $\hat { \beta } _ { 1 } ^ { \text {TSLS} } = \frac { S _ { Z Y } } { S _ { Z } ^ { 2 } }$