An open economy is characterised by a marginal propensity to save ($MPS$) of 0.12, a marginal propensity to tax ($MPT$) of 0.08, and a marginal propensity to import ($MPM$) of 0.05. The government increases capital expenditure on public infrastructure by £15 billion, which increases national income. This growth in national income subsequently induces private firms to increase their capital investment to meet the rising demand.

Which of the following correctly identifies the value of the national income multiplier and the economic concept that explains the subsequent induced investment?