The table below shows the p-value and adjusted R- of models predicting birth weight of babies where a forward-selection algorithm added variables to the model one-at-a-time. Based on this table, which variable should be added to the model first? variable gestation parity age height weight smoking status p-value 2.2 x 10-16 0.1052 0.2375 2.97 x 10-12 8.2 x10-8 2.2 x 10-16 R2 adj 0.1657 0.0013 0.0003 0.0386 0.0229 0.0569 gestation parity age height weight smoking status none